HRD of the single WN stars compared to the evolution tracks that account for very rapid initial rotation (v_rot> 500 km s^-1, Brott et al. 2011). These evolution models assume an initial metallicity of 0.14 Z_⊙ and were calculated roughly until the central hydrogen exhaustion. The labels close to the tracks refer to the initial mass. The color coding in the same as in Figs. 18 and 19 (see also the inlet).